Hydantoin diisocyanates

ABSTRACT

New bis-(1&#39;&#39;- gamma -isocyanatopropylhydantoinyl-3&#39;&#39;)-alkanes, for example 1,6-bis-(1&#39;&#39;-(- gamma -isocyanatopropyl)-5&#39;&#39;,5&#39;&#39;dimethylhydantoinyl-3&#39;&#39;)-n-hexane and 1,1&#39;&#39;-methylene-bis-(3- gamma -isocyanatopropylhydantoins), for example 1,1&#39;&#39;-methylene-bis-(3gamma -isocyanatopropyl-5,5-dimethylhydantoin), and their use for the manufacture of polyurethanes by reaction of the new diisocyanates with polyhydroxyl compounds. The new diisocyanates are completely odorless and an irritation of the mucous membranes by these new diisocyanates has hitherto not been observed. The new diisocyanates are therefore preferentially used in the lacquer field.

United States Patent Haug et al.

[451 July 11, 1972 [54] HYDANTOIN DIISOCYANATES [72] Inventors: I Theobald Hang, Frenkendorf; Hans [30] Foreign Application Priority Data April 15, 1969 Switzerland ..5664/69 [52] U.S. Cl ..260/309.5, 26( )/2.5 AT, 260/47 CB, 260/75 NT, 260/77.5 NC, 260/77.5 CH, 260/77.5 AT [51] Int. Cl. ..C07d 49/32 [58] Field of Search ..260/309.5

[56] References Cited UNITED STATES PATENTS 3,391,097 7/1968 Williamson ..260/3095 3,449,353 6/1969 Porret et al ..260/309.5 3,542,803 11/1970 Porret ..260/309.5 3,591,590 7/l97l Haug et al ..260/309.5 3,592,823 7/1971 Porret ..260/309.5

Primary ExaminerNatalie Trousof AttorneyI-larry Goldsmith, Joseph G. Kolodny and Mario A. Monaco [57] ABSTRACT New bis-( 1-'y-isocyanatopropylhydantoinyl-3 )-alkanes, for example l,6 -bis-[ l '-(-y-isocyanatopropyl)-5 ',5 '-dimethylhydantoinyl-3']-n-hexane and 1,1-methylene-bis-(3 y-is0- cyanatopropylhydantoins), for example l,l-methylene-bis- (3-y-isocyanatopropyl-5,5-dimethylhydantoin), and their use for the manufacture of polyurethanes by reaction of the new diisocyanates with polyhydroxyl compounds. The new diisocyanates are completely odorless and an irritation of the mucous membranes by these new diisocyanates has hitherto not been observed. The new diisocyanates are therefore preferentially used in the lacquer field.

6 Claims, No Drawings 1 2 HYDANTOIN DIISOCYANATES polyureas for certain applications. In contrast to the aliphatic and aromatic diisocyanates which are not physiologically It is known to react organic molecules which contain one or harmless, such as l,6-hexsmethylenediisocyanate and more isocyanate groups, with organic compounds which postoluylcnediisocyanate, the new diisocyanates are completely sess one or more OH groups. Urethanes are thereby obtained. 5 odorless and an t t n Of t mu u m m an s by th se Fundamentally it is possible to add all hydrogen atoms w dii cyanate has hithert n t be n servedreplaceable by alkali metal in organic molecules to isocyanate The u j of th p e ent 6 0n are us n inucl fl groups. N-heterocyclic diisocyanates of formula (CH:)3N=C=O O:C=N-(CH); I CN\ /N 0:0 /R /CN\ z \N --v 1 1 m' Organic diisocyanates or polyisocyanates are extensively wherein Z represents a divalent aliphatic, cycloaliphatic or used for the manufacture of polyurethanes. For this purpose, araliphatic radical, and in particular preferably an alkylene organic diisocyanates or polyisocyanates are reacted with radical or an alkylene radical which is interrupted by oxygen 'diols or polyalcohols, for example polyester glycols or atoms, and R,, R R and R independently of one another polyether glycols. In accordance with the isocyanates and alea h denote a hydrogen atom r an aliphatic, c cloali hatic, COhOlS p y and wing suitable Prosesses, polyuaraliphatic or aromatic hydrocarbon radical, such as esperethanes are thereby Produced which find as fibers, films, cially a lower alkyl radical with one to four carbon atoms, alfoams, adhesives or mouldings. The manufacture of polyukeny] with two to four carbon atoms, cyclohexyl, cyclohexorethanes is described in summary in Vieweg-Htichtlen, Kunstn l r hen l or wherein R, and R and/0r R, and R stoffl'landbuch (Pla tic H ndb k) V l 7, p ge 2 7 and together form a divalent aliphatic or cycloaliphatic hydrocarthe a t rbon radical, preferably a tetramethylene or pentamethylene Further, organic diisocyanates or polyisocyanates can be di l, used for the manufacture of Polyureas, wherein Organic (1550- According to the invention, the new diisocyanates of formucyanates or polyisocyanates are reacted with organic diamines l (1) can b manufactured b r a ti diamines of formula (II) o 0 ll (CH2)3 NH2 H2N(CH2)a- CN\ kN-O R\ /C: Z O=C\ R1 /CN\ /NC/ J R: Rz'

or polyamines. Since the isocyanate group can add to urea wherein Z, R,, R R and R have the same significance as in groupings already formed, branched or crosslinked polyureas formula (I), with phosgene. In doing this, it is preferred to containing biuret groups are easily produced. start from the hydrochlorides of the diamines of formula (ll), The diiso y n used in in y, such as for example which are then reacted with phosgene in o-dichlorobenzene or am hylenediisocyanate, phenyl-l ,4-diisocyanate toluylen other organic inert solvents at to 170 C. Another process 2,4-diisocyanate and yl y n possess nconsists of first converting the diamines of formula (II) by pleasant physiological properties, for whiCh reason their means of carbon dioxide into the corresponding carbamic pr essi g dema d p PrOIBCtiVF rneasal'es these 50 acids or their betaine-like salts and then to phosgenate these. alsadvaniageous p gs s to be ellmlnated y A further method is the dropwise addition of the solution of 3 dllsocyanates h'gher molecular ffy of the diamines of formula (ll) to a cooled solution of phosgene f l Y- pl 2,440]uylefle'dllsocyanate in an inert solvent. Furthermore, the new diisocyanates of fordlmensed to give y y 'p yn' mula (l) are produced according to a continuous process, in

uretdlone P ofMeSSrs- Bayer, commercially available which phosgene and the diamine solution are simultaneously under the registered trade name Desmodur TT), 3 added to a hot, inert solvent, with the diisocyanate solution molecules of zt+t9luylenediisocyanate are added to being withdrawn from the reaction vessel, equipped with an molecule of lll'mmethylolpropaner h F overflow, at the same rate as the addition of the diamine soluisocyanate containing urethane groups, which In the ideal case on is trifunctional, is produced (aproduct of Messrs. Bayer, com- The diamines of formula (H) are obtained if the mercially avmlable, under, the reglstered trade name cyanoethyl) compounds obtained by cyanethylation of the Desmodur L", having an lsocyanate content of about 19.2 corresponding binuclear hydamoins offormula percent), or 3 mols of l,6-hexamethylenediisocyanate (registered trade name Desmodur H) are reacted with one mol (III) of water, whereby an aliphatic isocyanate containing biuret 0 H groups, which in the ideal case is again trifunctional, is l g produced (a product of Messrs. Bayer, commercially available I under the registered trade name Desmodur N, having an I 0: l R1 isocyanate content of 26.3 percent). 0-

It has now been found that the use of certain diisocyanates which have hitherto not yet been described in the literature and which contain two heterocyclic nuclei, and in particular are hydrogenated in amanner which is in itself known. l,l '-methylene-bis-(3-'y-isocyanatopropyl-hydantoins) and The diisocyanates of formula (I) comprise two preferred 3,3'-alkylene-bis-(l y-isocyanatopropyl-hydantoins) is parsubdivisions. The first subdivision of the new diisocyanates ticularly interesting for the manufacture of urethanes and corresponds to the formula wherein R,, R,', R and R have the same significance as in formula (I).

As examples of the new diisocyanates of formula (V) there may be mentioned: 1,1 -methylene-bis-(3-y-isocyanatopropylhydantoin); 1,1'-methylene-bis-(3-y-isocyanatopropyl-5,5 -dimethylhydantoin; l,l-methylene-bis-( 3-y-isocyanatopropyl-S-methyl-S-ethylhydantoin) and 1,1 methylene-bis-(3-y-iso-cyanatopropyl-5-isopropylhydantoin).

The binuclear hydantoins used as starting substances for the manufacture of the new diisocyanates of formula (IV) correspond to the formula wherein Z, R,, R,, R and R have the same significance as in formula (I), and can be obtained in accordance with the process described in U.S. Pat. specification No. 3,296,208 by condensation of 1 mol of each of the two hydantoins of formulas (Vll a and V" b can be identical or different hydantoins) with 1 mol ofa dihalide of formula Hal Z Hal (VIII) wherein Hal represents a halogen atom and Z has the same significance as in formula (I), in the presence of 2 equivalents of alkali.

The binuclear hydantoins used as starting substances for the manufacture of the new diisocyanates of formula (V) correspond to the formula 1111 1 lIN3 IN-CIII IWNI 3NII ll ll 0 wherein R R,, R and R have the same significance as in formula (I), and can be easily obtained in accordance with the process of U.S. Pat. specification No. 2,4l7,999 by condensation of 2 mols of a hydantoin of formulas (Vll a) and (VII b) with 1 mol offormaldehyde.

As initially mentioned, it is possible to add all hydrogen atoms replaceable by alkali in organic molecules to isocyanate groups. As examples of such compounds or classes of compounds there may be mentioned: alcohols, amines, carboxylic acids, phenols, ureas, urethanes, hydrazines, water, ammonia, hydrogen sulphates, imines, thioureas, sulphimides, amides, thiols, amino-alcohols, sulphonamides, hydrazones, semicarbazones, oximes, hydroxycarboxylic acids, aminocarboxylic acids as well as all polymers which contain active hydrogen atoms in the form of hydroxyl, carboxyl or amino groups and the like. The isocyanates of formula (I) can be employed for the polyaddition or crosslinking either by themselves or in mixtures with other isocyanates, diisocyanates or polyisocyanates. Depending on the nature and amount of the crosslinkings, it is possible to manufacture both very firm brittle compositions and also plastics with rubbery-elastic properties.

ln order to manufacture thermoplastics, the diisocyanates of formula (I) can be reacted with glycols, such as ethylene glycol, 1,3-propylene glycol, 1,4-butanediol or with any desired dialcohols, which can also carry isocyclic, aromatic, heterocyclic or linear hetero groupings, as well as ester groupings.

Possible crosslinking agents or curing agents are above all those classes of compounds which yield three-dimensionally crosslinked, infusible and insoluble products with the diisocyanates of formula (I).

As crosslinking agent or curing agent of this nature, polyhydroxyl compounds are above all employed. The following may for example be mentioned: polyesters, containing hydroxyl groups, of adipic acid, phthalic acid or dimerised unsaturated fatty acids with diols and/or triols, such as ethylene glycol, 1,4-butanediol, l,5-pentanediol, glycerine, and diethylene glycol; castor oil; linear or partially branched polypropylene ether glycols and polytetramethylene ether glycols; polythioether glycols and polyacetal glycols; sugars and sugar derivatives; higher-functional polyols, such as trimethylolpropane.

Further possible crosslinking agents are above all the polyamines, especially aromatic polyamines, such as 4,4- diaminodiphenylmethane, as well as those compounds which simultaneously contain hydroxyl and amino groups, such as for example tri-isopropanolamine.

The polyaddition reaction of glycols, polyhydroxy compounds and polyamino compounds with the diisocyanates of formula (I) can be carried out directly without diluents, temperatures in the range of about 50 to 300 C. being required depending on the nature of the reaction components. It is also possible to carry out the process in diluents, for example halogenobenzenes.

The molecular weight of the polyurethane can be varied in a manner which is in itself known, depending on the variation of the molar ratio of the components, the removal of the heat of reaction from the melt, the increase in the dwell time in the dissolved state and the addition of monofunctional, that is to say chain-stopping, components. In general, it is necessary, for use in the plastics field, to polymerize up to an average molecular weight of about 6,000. Low molecular types are primarily of interest for the lacquer field.

The polyaddition reaction can also be carried out in the presence of accelerators; this is however not imperatively necessary. Possible catalysts are especially tertiary amines, such as pyridine, N,N'-dimethylpiperazine, N,N-dimethylbenzylamine, tributylamine, triethylamine, N-methylmorpholine, N-methylpyrrole, N-methylpyrrolidine, diaza- (2,2,2)-bicyclooctane or diethyl-2-hydroxyethylamine, and also metal salts, such as FeCl AlCl ZnCl SnCl tin" isooctoate, lead octoate, lead naphthenate and the dilaurate of tindibutyl. A survey of the most customary catalysts is furthermore to be found in "Houben-Weyl", 4th edition, volume XIV/2, on page 61 (Review by E. Miiller).

For the manufacture of foams, blowing agents and surfaceactive substances, such as for example silicone compounds, as foam stabilizers can furthermore be conjointly used, in a manner which is in itself known.

The manufacture of polyurethane plastics products is as a rule carried out with simultaneous shaping to give castings, foam articles, pressings, lacquer films, laminates, adhesive bonds and the like. In manufacturing these, the procedure followed is that a mixture of the diisocyanate of formula (1) and the polyhydroxyl compound, as well as the optionally conjointly usedcatalyst and/or blowing agent, foam stabilizer and the like, is prepared and this mixture is then, after introduction into casting or pressing moulds, spreading as coatings, introduction into adhesive joints and the like, allowed to react, with application of heat, to give the plastic.

The subject of the present invention are therefore also moulding compositions which can be converted, under the influen'ce of heat, into mouldings or foam articles, including two-dimensional structures, such as coatings or adhesive joints, and which contain (a) a binuclear N-heterocyclic diisocyanate of formula (1) and (b) a polyhydroxyl compound and also, optionally, a curing catalyst and/or blowing agents and foam stabilizers.

Of course further customary additives for polyisocyanate moulding compositions, such as fillers, reinforcing agents, mould release agents, antioxidants, anti-ageing agents, light protection agents, UV-absorbers, flameproofing substances, optical brighteners, dyestuffs or pigments can be added to the moulding compositions.

Suitable fillers or reinforcing agents are fibrous or pulverulent inorganic, as well as organic, substances. The following may be mentioned: quartz powder, aluminum oxide trihydrate, mica, aluminum powder, iron powder, iron oxide, ground dolomite, chalk powder, gypsum, slate powder, unburned kaolin (bolus), glass fibers, boron fibers, carbon fibers, asbestos fibers, and especially fillers of high water absorbency, such as for example anhydrous silicon dioxide, silica aerogel,

anhydrous aluminum oxide, active charcoal, zeolites, bentonites and burned kaolin.

The moulding compositions can, in the unfilled or filled state, furthermore serve as dipping resins, casting resins, laminating resins, impregnating resins, lacquers, coating agents, sealing compositions, potting and insulating compositions for the electrical industry, or adhesives.

In addition to manual handling, the mechanical methods of handling for the manufacture of polyurethane plastics can appropriately be employed which permit continuous mixing of the diisocyanates (a) with the components (b) containing hydroxyl groups, to form a homogeneous melt. Thus the most diverse moulded articles (hard rubber substitute) can be manufactured by casting or by centrifugal moulding. Further uses exist in the field of casting compositions for filling joints by casting or sealing pipe couplings, and as floor surfacings or road surfacings, impression compositions or adhesives. It is simple to manufacture unsupported films, strips or filaments and to carry out impregnations or coatings of textiles, fiber materials (leather substitute) or paper. The new moulding compositions can, if the reaction speed is appropriately adjusted, for example serve for lining containers or for the manufacture of endless tubes of anyprofile by means of continuously operating heated injection moulding machines. Stiff foams or rigid foams manufactured from foam compositions according to the invention are for example used as insulating substances for buildings and refrigeration installations, as packaging materials and above all for shock absorption, for example as vibration-damping constructional units in automobile construction and machinery construction.

in the examples which follow parts denote parts by weight and percentages denote percentages by weight, unless otherwise stated. The relationship of parts by volume to parts by weight is as of the millilitre to the gram.

EXAMPLE 1 Hydrochloric acid gas was introduced for 30 minutes into a solution of 50.0 g of crude 1,1'-methylene-bis-(3- aminopropyl-S,S-dimethylhydantoin) in ml of absolute ethanol, while cooling in a bath of ice. The salt which precipitated in the course thereof was filtered off, washed with ice-cold absolute ethanol and dried, whereby 47.0 g of colorless hydrochloride of melting point 263 64 C. were obtained.

calculated:

C 44.84 found: C

calculated: found:

The H-NMR (nuclear magnetic resonance) and [R (infrared) spectrum agree with the assumed structure. The

resulting diisocyanate accordingly has the formula EXAMPLE 2 Hydrochloric acid gas was passed for 60 minutes into a solution of 697 g of crude l,6-bis-[1'-('y-aminopropyl)-5',5'- dimethylhydantoinyl-3']-n-hexane in 2,500 ml of absolute ethanol, while cooling in an ice bath. The salt which precipitated in the course of this was filtered off, washed with ice-cold absolute ethanol and dried, whereby 749 g of colorless hydrochloride of melting point 238 40 C. were obtained.

C H.,,,N,,O. 2 HC] (525.52)

calculated: found:

Cl 13.49 N 15.99 Cll3.1l N 15.55%

Phosgene was passed for 8 hours at 150 C. into a suspension of 208 g (0.389 mol) of the hydrochloride in 2,000 ml of dry o-dichlorobenzene. 1n the course of this, the suspension changes into an almost clear, light brown solution. The slight precipitate was filtered off and the clear solution was concentrated in vacuo to constant weight. 198.0 g of brown-colored, initially viscous, slowly crystallizing 1,6-bis-[1 -(y-isocyanatopropyl)-5 ',5 '-dimethylhydantoinyl-3 ']-n-hexane were left, with an isocyanate content of 15.4 percent (92.4 percent of theory).

The H-NMR and IR spectrum agree 'with the assumed structure. Accordingly, the resulting diisocyanate has the formula 7 8 (EH3 (EH3 CH3(|J?=O O=C-CCH3 OCN--CH2-CHz-CH2--N N-(CH2)&N\ /NCH2cII2CI{ -NC C C ll 0 0 EXAMPLE 3 1:1 50 percent strength lacquer solutions were prepared in A l i f 3() g f ubi q1' i 1 5' each case by adding further solvent mixture of ethylglycol dihydantoinyl-3]-diethyl ether in 40 ml of chloroform was 10 acetate/methyl ethyl ketone/totuene in the weight ratio of slowly added dropwise, with good cooling and vigorous stirtitit- These lacquer Solutions were pp to Previously ring, to a mixture of chloroform/diethyl ether in the weight cteaned aluminum Sheets, cured under the Conditions ratio of 1:1, and at the same time hydrochloric acid gas was dtcated in the tabte belowand the P P of the Cured passed into this solvent mixture. As a result, the hydrochloride l5 lacquer Subsequentty ttetetmtnedprecipitated as an almost colorless, solid resin, which weighed y y of compansonv two known 50 Percent strength 31 g after fil i ff d d i ph was passed i lacquer solutions were manufactured, wherein, instead of the a suspension of 18.0 g (0.035 mol) of the powder d new diisocyanates A or B, 2.4 g of l.o-hexamethylene-diisohydrochloride in 300 ml of o-dichlorobenzene at 140 C. for 6 cyanate ii y nate 01' 7.2 g of a trifunctional polyist hours, with vigorous stirring. in the course thereof, the suspencyanate (p yi yana n ng biuret groups and obsion han ed to a l r brown l ti hi h was concentainable by reaction of 3 mols of 1,6-hexamethylenediiso- {rated to on tant wei ht in a 17,2 g f b hi hl cyanate with 1 mol of water, which is commercially available viscous B,B'-bis-[1-( isocyanato ro l)-5',5-dimeth lh from Messrs. Bayer under the registered trade name dantoinyl-3]-dietl1yl ether were left, with an isocyanate con- Desmodur N", were used respectively. The known diisotent of 14.3 percent (83.6 percent of theory). cyanate or polyisocyanate C and D respectively were mixed The H-NMR and lR spectrum agree with the assumed strucwith the same amount of Desmophen 650" (10 g) and the ture. same organic solvent mixture, and the lacquer solutions thus Accordingly, the resulting diisocyanate has the formula: Obtained were applied, cured and tested as described above.

(EH3 $Ii3 CH1C-(iJ=O O=CCICH3 O CNCHZCII2-CH2N NCH2CH2-*OCH2CH2N /NCHz-CHCHNCO r \C 0 ll EXAMPLE 4 The table which follows contains the comparison of the properties of lacquers which were manufactured using diisocyanates A, B and C and polyisocyanate D. Table: Properties of lacquer solutions of polyester alcohol (Desmophen 650) and various diisocyanates or polyisocyanates.

A glass vessel which could be heated and was provided with an overflow was charged with dry o-dichlorobenzene and the latter heated to about 165 C. A solution of 20.0 g of 1,1- methylene-bis-(3-y-aminopropyl-5-isopropylhydantoin) in 40 380 ml of dry o-dichlorobenzene was added dropwise at this n v temperature over the course of 200 minutes, whilst phosgene gg g 'g 3: 1 g 'f was simultaneously passed into the vessel. The liquid volume A B C D in the reactor was always constant, since a diisocyanate solution was withdrawn by means of the overflow corresponding pot life of a to the addition of diamine solution. After completion of the smug", lacquer addition, the solvent was distilled off and 2l.l g of viscous sohmon in ethyl- 2.0 L5 substance with an isocyanate content of 17.24 percent (95 gly l acetate:

methyl ethyl ketone: days days days days 50 toluene l:l:l parts by weight) percent of theory) remained.

elementary analysis: C H N O (462.5) at 20C/65% relative calculated: C 54.53 H 6.54 N l8.l7 humidity the lacquer l9 l5 l9 18.5 found: C 54.58 H 6.4! N 17.76 is dust-dry after hours hours hours hours after curing at 20C the pendulum hard- The H-NMR and IR spectrum agree with the assumed struc- Hess according to ture. Accordingly, the resulting diisocyanate has the formula: pmoz CH(CH:)2 omen ():':CC*ll II-(JC:O

0 II II 0 USE EXAMPLE after I day 90 92 ll l 88 10 g portions of a percent strength solution of a 3 days 243 196 288 285 7 days 335 220 330 346 polyester-alcohol with an acid number of less than 4 and an pendulum hardness OH group content of about 8 percent (a commercial product according to available from Messrs. Bayer under the registered trade name Per01(after 390 3 0 395 390 Desmophen 650) in an organic solvent mixture consisting 120 C for 60 minutes) of ethylglycol acetate/methyl ethyl ketone/toluene m a weight resistance to acetone ratio of l:l:l were mixed, in a first sample, with 8.2 g of 1,1 after curing at l20C/60 minutes tacky tacky tacky tacky me..thylene bls (3 y lstxyanatopropyl ihmethylhydammr} at l50C/l20 scratchscratchscratchscratch (diisocyanate A) and in second samples with 7.90 g of l,6-bisminutes resis resis rub (l-('y-isocyanatopropyl-5',5-dimethylhydantoinyl-3)-n-hexmm mm lam resistant ane (diisocyanate B) (ratio of HO groups to OCN groups The comparison shows that the pot life of lacquer solutions based on the diisocyanate A according to the invention and the diisocyanate 13 according to the invention is longer than that of the two other lacquer solutions based on diisocyanate C and polyisocyanate D.

The pendulum hardness measured on lacquers after I day's curing at 20 C. or after 1 hours curing at 120 C. shows that using the bifunctional diisocyanates A and B lacquers are obtained which surprisingly are of equally high hardness as lacquers based on the trifunctional polyisocyanate D. Since lacquers which are based on trifunctional polyisocyanates, for example polyisocyanate D, possess a higher density of crosslinking points, it would have been expected that the lacquers from the diisocyanates A and B would show distinctly worse properties. The lacquers based on the diisocyanates or polyisocyanates A, B or D are acetone-resistant after two hours curing at 150 C., in contrast to a lacquer based on diisocyanate C. This diisocyanate, which admittedly also yields lacquers of usable hardness, is however not directly used as a lacquer raw material because of its relatively high vapor pressure and the toxic effects resulting therefrom.

We claim:

1. A diisocyanate of formula C ll ll wherein Z represents alkylene of up to 12 carbon atoms which may be interrupted by oxygen atoms, and R R R and R each represents a member selected from the group consisting of hydrogen atom, alkyl of one to four carbon atoms, alkenyl of two to four carbon atoms, cyclohexyl, cyclohexenyl and phenyl or wherein R and R and/or R, and R together form a divalent residue selected from the group consisting of tetramethylene and pentamethylene.

2. A diisocyanate of formula mg I V UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent: No. 3, 7 ,455 Dated July 11, 1972 THEOBALD HAUG ET AL Iriventofls) It is certified that error sp'pears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Cover a e; after "[73] Assigneez" delete Ciba Geigy Corporation" and insert CIBA-GEIGY AG, Basle,

Switzerland Signed and sealed this 23rd day of April 19m.

' (sEAL) Attest:

C. MARSHALL DANH Commissioner of Patents EDL'JARD M.FLETGHER,JR. At testing Officer 

2. A diisocyanate of formula
 3. 1,1''-Methylene-bis-(3- gamma -isocyanatopropyl-5,5-dimethylhydantoin).
 4. 1,1''-Methylene-bis-(3- gamma -isocyanatopropyl-5-isopropylhydantoin).
 5. 1,6-Bis-(1''- gamma -isocyanatopropyl-5'',5''-dimethylhydantoinyl-3'')-n-hexane.
 6. Beta , Beta ''-Bis-(1''- gamma -isocyanatopropyl-5'',5''-dimethylhydantoinyl-3'')-diethyl-ether. 